Variations of the crustal thickness in Nepal Himalayas based on tomographic inversion of regional earthquake data

摘要

We estimate variations of the crustal thickness beneath the Nepal Himalayasbased on tomographic inversion of regional earthquake data. We have obtaineda low-velocity anomaly in the upper part of the model down to depths of 40 to80 km and proposed that the lower limit of this anomaly representsvariations of the Moho depth. This statement was supported by results ofsynthetic modeling. The obtained variations of crustal thickness match fairlywell with the free-air gravity anomalies: thinner crust patterns correspondto lower gravity values and vice versa. There is also some correlation withmagnetic field: higher magnetic values correspond to the major areas ofthicker crust. We propose that elevated magnetic values can be associatedwith more rigid segments of the incoming Indian crust which cause morecompression in the thrust zone and lead to stronger crustal thickening.